tabBuilder property

An IndexedWidgetBuilder that's called when tabs become active.

The widgets built by IndexedWidgetBuilder is typically a CupertinoTabView in order to achieve the parallel hierarchies information architecture seen on iOS apps with tab bars.

When the tab becomes inactive, its content is still cached in the widget tree Offstage and its animations disabled.

Content can slide under the tabBar when they're translucent. In that case, the child's BuildContext's MediaQuery will have a bottom padding indicating the area of obstructing overlap from the tabBar.

Must not be null.